Telephone-exchange system



Jan. 4 1927.

G. H. PETERSON TELEPHONE EXCHANGE SYSTEM Fi d June 18 1925 4 Sheets-Sheet 1 3 WC 47f] mzssn Jana I 27 ca. H. PETERSON TELEPHONE EXCHANGE SYSTEM Filed June 18 1925 4 Sheets- Sheet Jan. 4,, 1927. ,880

G. H. PETERSON TELEPHONE EXCHANGE SYSTEM Filed June 18 1925 4 Sheets-Sheet s Jan. 4 1927,,

PETERSON TELEPHONE EXCHANGE SYSTEM 4 Sheets-Sheet 4 Filed June 18 1925 wwh wk \E M n w m w 1W RM Nh W 0., w a. f w & W

Patented Jan. 4, 1927.

MNETED STATES PAii. El.

GEORGE E. PETERSON, OF BROQKLYN, NEW YORK, ASSIGNOR T AMERICAN FELT:-

PHONE AND TELEGRAPH COMPANY, A CORPORATION OI NEW YGRK.

TELEPHGNE-EXCHANGE SYSTEM.

Application filed June 18, 1925.

This invention relates to telephone exchange systems and particularly to circuits for establishing connections between mechanical and manual offices of such systems.

It has heretofore been the practice in es tablishing connections between a mechanical otlice of a stepby-step machine switching exchange and a manual office of such ex change to provide trunk circuits incoming from the full mechanical step-by-step ofiice to the manual ofiice, any one of which may be reached from any line in the full mechanical step-by-step ofiice. By removing the receiver at the station associated with said line and dialing a predetermined digit or con'ibination of digits known as the office code, the trunk circuit is selected and in turn is extended into connection with a preselected common circuit, known as a recorder and regrster circuit. Following the dialing of the code digits, the digits of the numerical portion of the wanted line number are dialed and recorded in the recorder and register circuit. After all the digit impulses required are received, the register circuit proceeds in combination with an indicating device such for example as disclosed in the Patent No. 1,572,679 issued Feb. 9, 1926, to

Albert C. Powell, to display the number of the desired called line before an operator in the manual otfice, who thereupon completes a connection to the called line. Signaling follows automatically and when the called. party answers the talking circuit is autinnatically established.

In small exchange areas it is possible to reach all o'l'lices of the area and all special service positions by dialing only one code digit thus setting a first selector. If the area cu'ibraces a rapidly expanding community or it is probable that adjoining exchange areas may in the future be joined to the original area. it is desirable to initially provide for access to a larger number of otlices than are initially installed, the larger number of oliices being reached by setting two selectors through the dialing of two oilice code digit. In this case it is desirable to instruct subscribers to dial two code digits printed in the directory although only one of these digits may initially he required for setting switches. It therefore is necessary to dispose of one of the code digits dialed since it is not used to set a selector switch and it recorded at Serial No. 38,058.

the recorder of a manual otlice would cause the display of a Wrong number before the operator.

The object of this invention is the pr. vision of improved means to connect any line in a full mechanical stepby -step oi'fice to any desired line in a distant manual office.

A feature of this invention is the provision of means for recording impulses transmitted by a dial or impulse repeater, and whereby the first series of impulses dialed into the repeater is rendered ineffective or absorbed.

Another feature of this invention is the provision of a relay for absorbing the first series of impulses received whether it be the first one dialed or not.

Other features will, appear from the detailed description.

Figure 1, in its upper left hand corner, shows a calling subscribers station A in a full mechanical step-by-step machine switching system, a diagrammatic representation of the usual primary and secondary switches PLS and SLS, a first ollice selector S and a repeater It all located in the. mechanical office X, and a trunk circuit extending to the manual office Y terminating in the plug 1 (Fig. 2) thereat. In the lower left portion of l is shown a recorder finder individ ual to the trunk circuit, having access to a plurality of recorders and registers, one of which is disclosed in Figs. 3 and et. There are two recorder finders associated with each operators position. The trunks at eachposition are divided in two groups, one half to the right of the operator and the other to the left. The trunks at the right hand group are associated with a finder such as 150, while a similar finder serves the left hand group. Conductor 135 shown in the lower left hand corner of Fig. l is used with the recorder finder serving the left hand group.

Fig. 2 shows the terminating end of the interoffice trunk disclosed in Fig. l and the line of a subscriber B terminating in the manual oifice Y.

Fig. 3 shows a recorder circuit and Fig. t shows a register circuit individual to the recorder circuit of 4.

To completely disclose the invention, 2 should be placed to the right of Fig. 1. Fig. 3 should be placed beneath Fig. 1 and Gil Fig. l should be placed to the right of Fig.

In general, the system functions in the following manner:

A calling subscriber A, Fig. 1, in the full mechanical step-hy-step otfice, desiring to communicate with a called. subscriber B, Fi 2, in a distant manual. oifice, removes the receiver from the switchhool; at station A and dials the desired number. Removing the receiver causes the primary and secondary line switches PLS and SLS, Fig. 1, to function and extend the calling line to the first or office selector S. The first digit in the se 'ies of digits dialed by the calling station known as a code or office digt and causes the selector to extend the calling line to an idle trunk circuit outgoing to the proper manual otlice. In series with this outgo trunk circuit at the mechanical oilice, is repeater 1% for receiving the impulses produced in the calling line circuit by the dial and relaying them over the impulsewcircuit to a recording device associated with the trunk circuit selected in the distant manual central ofilce. The recording device is equipped with suitable means for receiving the impulse transmitted by the repeater R, of recording them, and visibly displaying to the operator at the manual central office, by a suitable indicating means, the number of the desired called line. These indicating means are explained in detail in the above n'ientioned patent to Powell. The recording deyice is equipped with a means which al Serbs the first digit received without registering it. The operator at the manual otlico Y then inserts the plug P of the trunk into the jack J of the called line and the called station 13 is automatically signaled. When the called station responds, the talking circuit is established and'the conversation takes place. After the called number has been displayed before the operator in the manual central otfice, the recording and registering device, Figs. 3 and 1, having completed their functions,are released so as to render them available to other trunks in the group if required. .Vhen the conversation is finished and both stations disconnect, the manual operator at the central oiiice Y receives a signal and removes the plug of the trunk circuitfrointhe jack, thereby restoring the circuits to normal.

Having described the operation of the system in a general way, it is believed that its operation may be more clearly understoodfrom a detailed description which follows. i v

When the receiver is removed from the switchhool; at the calling station A, a circuit is closed including the calling station and the primary line switch PL extending the calling line to the secondary line switch SLS which in turn operates and extends the calling line to the first or office selector circuit S. The dial 100 is now operated and released and the selector S functions to select an idle trunk in the groups of trunks outgoing to the distant manual otlice Y. It will be assumed. that the trunk shown in part in Fig. 1 is the one selected, in which case the calling line A is extended to the repeater R which operates and closes a brid e across the conductors and 106 to operate the impulse relay 101 as follows: battery, through the, left winding of relay 101, left back contact of relay 107, conductor 108, inner ri ht back contact of relay 12S, conductor 10o, bridge circuit of repeater R, coruluctor 10%, enter l t back contact of relay 128, conductor 117, right back contact of relay 107 to ground through the right winding of relay 101. The windings 109 and 110 of the repeating coil are short-circuited at this time to prevent distortion of the impulses tr :itted over line to operate the inu ilsc 101, hereinafter fully described. Relay 102 operates over an obvious clrcuit to ground on the front contact of relay 101. The operation of relay 102 closes 2 circuit for operating relay 103 as follows: battery, winding and back contact of the stepper 118 of finder switch 150, conductor 119, right winding of relay 103, conductor 120, brush and are 115, conductor 121, outermost right back contact of relay 122, conductor 123, right back contact of relay 12 1-, conductor 139 to ground on the left front contact of relay 102. Stepper 118 does not operate, due to the high resistance of relay 103 in series with it. Relays 10 1 and 301 now operate in series as follows: battery, through the winding of relay 301, conductor 131, fourth tern'iinal and brush of are 112, conductor 125, windin of relay to ground on the inner righti'ront contact of rela 103. Relay 302 now operates in an obvious circuit to ground on the outer rightfrout contact of relay 301. Relay 103 in operating connects ground through its right front contact to brush 110, thereby grounding its :fourth ter minal which is multipled over lead to all other switches in the group, thereby making that terminal busy to all other switches.

The recorder finder switch is arranged to pre-select an idle recorder circuit, hence all other recorder finder switches which may be resting upon the multiple terminals of this recorder circuit must now he stepped to the terminals rssociated with the next idlerecorder circuit. This is accomplished as follows: Individual to each trunk circuitis a relay 12? which. whenever any trunk circuit is not in use, is connected to battery through the inner left contacts of a relay 122, also individual to such trunk, and through the right back contac or": re ay 10?;

of such trunk to brush 110 of the trader such trunk. Arssuming that sociated with (ill the brushes of some other recorder finder switches, corresponding to the brushes or finder 150 are restin uon the terminals corresponding to terminal 4 of the recorder tinder 150, parallel circuits through all corresponding relays 127 will be connected by way of the n'mltiples to terminal ii: of arc and brush 110 to ground on the right front contact of relay 103 of the trunk circuit in use. The various relays 127 will operate and close obvious local circuits to operate the various associate stepper magnets similar to 1.18, and in releasing will step their recorder finder switch, brushes to the termia ls of the first recorder circuit in the group which is not busy. ll henever the recorder finder switch brushes come to rest upon the test terminal of an idle recorder circuit, the ground to hold relays 123 operated will b removed and these rela s will release, prcventing the associated stepping magnets from rotating the switch brushes any further until the seizure of another trunk circuit necessitates the occurrence of this cycle of operation. The. operation of relays 103 and 10l extends the leads 133, and 13% through the brushes 113, and 11% for a pur pose which will hereinafter he madcapparent.

It has been observed that the recorder circuit is made busy when relay 103 operates. This immediate busy condition is intended to prevent the possibility of a double seizure of a. recorder between the time the brushes come to rest upon the to ininals of a particular recorder and the time required to operate relay 302 which su plies ground to make the recorder circuit bu..-,y to all other recorder tinder switch 3 until the recorder circuit has completed its functions as hereinafter described. After relays 103 and 10% have operated, the recorder is ready to receive iinpi'llses.

In accordance with this invention. it is re quired that the :li digit received he ab sorbed and not form a part of the desired nuniber. 'lhercfore, when the dial 100 is operated by the calling station for the last code digit the pulses will be absorbed as will now be described. The dial 100 oper ated and released and as it returns to nor; al it interrupts the circuit including th station loop and the repeat-er R which in turn interrluats the circuit including the bridge of repeater R and relay 101. Relay 101 is a fast operating relay and is de. nod to follow the in'ipulses from repeater ll. This impulse circuit opeates relay 312 3 upon each deenergization of relay 101 over a circuit from ground, back Contact of relay 101, outer left back contact of relay right front contact of relay 102 conductor 13?. right back contact of relay 5211,- con ductor 214 outer left front contact of relay 103', brush 11- 1, conductor 134, left back contact of relay 303, conductor 30-l, inner left back contact of relays 30:5, 306, 307, 308 and 309, inclusive, conductor 310., conductor 311 to battery through the winding of relay 312. Relay312 operates in this circuit and being slow to release remains energized until the pulses for this digit cease. Upon energizingr it closes a circuit for operating relay 313 from ground on its front Contact, through the right back contact of relay 313. conductor 314, inner left front contact of relay 301 to battery at the winding of relay 313. Relay 313 operates and locks to ground on its right front contact under control of relay 301 and places a shunt around relay 305). which may be traced from ground on the front contact of relay 312, conductor 315, resistance 316, left front contact of relay 313, conductor 31.7 outer left back contact and winding of relay 309 conductor 318 outer left back contact of relay 305 to ground on the outer leftfront contact of relay 301. After the pulses for this digit have been re ceived, relay 312 releases and removes the shunt from around relay 309, allowing it to operate in a circuit from ground on the outer left front contact of relay 301, conductor 318, winding and left outer hack contact of relay 300, conductor 317, left front contact of relay 313 resistance 319, conductor 0 to battery through the outer right back contact of relay 305. Relay 309 operates and locks to battery on its outer left front conact.

The oiiieration of relay 300 closes the pulsing circuit for the next d1 which is the thousands digit from ground on the back contact of relay 101, outer left back contact of relay 122, right front contact of relay 102, conductor 15-3 1" rigrht hack contact of relay 211 conductor 14, left front contact of relay 103 brush and terminal of are 114., conductor 13%, le t bacl: contact of relay 303, conductor 304-, to battery through the winding; of relay and in parallel therewith through the inner left back contacts of relays 30-5, 306 307 and 308, inner left front contact of relay 309, conductor 320, normal contact and winding of magnet e03 the thensands register TH conductor 310, conductor 311 to battery through the winding of relay 312. Relay 321 operates to insure positive st pping of magnet @106 regardless of the duration of each clotre of the pulsing relay. The operation of relay 309 also closes a. holding); circuit for re ay extending from battery through th winding; of relay 321 he inner left oacl: con lots of relays a, (n 0, 30? and the inner left front contact of relay 309*, condo tor 320 back contact of n agnet 4-06 conductor 40 ri n f ont contact of relay 30%;), i 1 hack contacts of rela s 3051 30? and 3.10, inner right back contact of relay 305 right front con tact of relay 321 to ground through the outer r he) mature .of magnet 406 is fully attracted and closes an auxiliary or booster circuit to insure the proper operation of stepping magnet 406 as follows: ground on the right outer front contact of relay 301, right front contact of relay 321, inner right back contact of relay 305, right back contacts of relays 306, 307 and 308 and right front contact of relay 309, conductor 407," through the winding of stepping magnet 406 to battery through the winding ofrelay 3 12. Stepping magnet 406 in operating, opens the holding circuit through the relay 321 and when the impulse relay 101 reoperates and relay 321 releases, the circuit through stepping mag-net 406 and the initial circuit of relay 321 are opened. Magnet 40,6 releases and on its backward stroke rotates the brushes of register TH, one step in a counter-clockwise direction tothc first terminal. With the brush associated with are 405 resting upon the ii rstterminal, a circuit is closed from ground on the outer left front contact: of relay 301, conductor 3' 8 winding of relay 308, outer left back contact of relay 308, conductor 322, brush and No. 1 terminal of are 405, conductor 3-71, resistance 319 conductor 370 to battery on the outer right back contact of relay 305. The stepper 406 rotates the brushes of register TH step byestep in this manner. until the train of impulses produced by relay 101 ceases.

After the last impulse of the thousands digit of the impulse train ceases, relay 312 which energized in series with magnet 406 releases, removing the low resistance shunt 316 from around relay 308, which now opcrates and locks to battery over its outer left front contact. lVith relay 308 energized the impulsing and booster circuits are transferred at its right and inner left armatures, respectively, from the stepping magnet 406 of the thousands register switch TH to the stepping magnet 416 of the hundreds register switch H.

The digit corresponding to the hundreds digit of the desired number is now dialed at station A and the stepping magnet 416 operates and rotates the register switch which takes the proper setting in the same general manner as the thousands register switch. At the end of the impulse train relay- 307 operates and locks in the same general manner as relay 309 and transfers the impulsing and booster circuits at its right and inner left ari'natures respectively, to the stepping magnet 426 of the tens register switch. In like manner the tens digit is registered and relay 306 operates and locks and transfers the impulsing and booster cirunits at its right and inner left armatures respectively, to the stepper magnet 436 of the units register switch.

res-12sec In like manner the ,units digit is registered and upon the completion of the registration of this digit and the release of relay 312 a circuit is closed for relays 303 and 305 in.

parallel which may be traced from ground on the back contact of relay 312, conductor 324, brush and are 435, conductor 427 to battery through the operating winding of relay 303 and also through the right winding of relay 305, The operation of relay 30.) releases relays 306, 307, 308 and 309 as they have no further functions to perform at this time. The operation of relay 303 disconnects at its outer right and outer left back contacts the pulsing leads from the trunk in order to prevent any false operation of the recorder selector switches. Relay 303 also furnishes battery to light the associated trunk assignment lamp 201 over a circuit from battery through its inner right front contact, right winding, conductor 133, are and brush 113, inner right front contact of relay 104, conductor 138, assignment lamp 201, outer right back contact of relay 205, conductor 215 to ground at the outer right back contact of relay 203. The operator, upon noticing the lighted assignment lamp 201 operates the assignment key 216 which operates relay 203 over a circuit from ground on the left front contact of relay 102, conductor 139, inner left back contact of relay 209, conductors 217 and 218, upper contact of key 216 to battery through the right winding of relay 203. The operation of assignment key 216 also operates the indicator in the peg count circuit through the lower make contact of the key thereby registering the initiation of the call. Relay 203 upon operating closes a holding circuit for itself independent of key 216 from battery through both of its windings and inner left contact, thence to ground at the left contact of relay 102 as previously traced, and closes a circuit for holding relay 103 from ground on the outer left front contact of relay 203, conductor 212, left front contact of relay 104 to battery through the left winding of relay 103, thereby preventing its release when the circuit through its right winding is opened due to the later operation of relay Relay 203 also closes a circuit for operating relays 122 and 128 in parallel from ground on its inner right front contact, conductor 213, to battery through the winding of relay 122 and to battery through the winding of relay 128. Relays 128 and 122 lock over the inner left front contact of relay 128 to ground at the left contact of relay 102.

At this time relay 323 operates over a cir- 121 and @131 of the registers, thereby lighting the lamps in the position indicator associated therewith as explained in the patent to A. C. Powell, above mentioned. Relay 203 also disconnects steady ground from lamp 201 and connects interrupted ground through interrupter 20 1, outer right front contact of relay 203, conductor 215, outer right back contact of relay 205 through lamp 201, conductor 138, inner right front contact of relay 1, brush and are 113, conductor 133, right winding of relay 303 to battery on the right front contact of relay 303 thereby flashing the assignment lamp 201 as an indication to the operator that the call on the trunk has been indicated on her lamp indicator.

Relay 128 upon operating removes the shunt from around the windings 109 and 116 of the repeating coil thereby preparing the trunk for talking transmission, the repeating coil being shunted out of the circuit during pulsing to improve pulsing conditions. Relay 122 operated, disconnects the pulsing lead from the back contact of relay 101 thereby preventing any false operation from taking effect after assignment key 216 has been operated. The operation of relay 122 opens the circuit of relay 127 by disconnecting battery from its operating circuit at the inner left back contact of relay 122, and at its outer right back contact opens the circuit through the right winding of relay 103, but relay 103 does not release at this time as it is held operated through its left winding to ground on relay 203. Relay 122 also closes in part a circuit from battery through the disconnect lamp 210., right back contact of relay 209, conductor 219, inner right front contact of relay 122, which is now open at the outer right contact of relay 10 1.

llpon the operators ascertaining the number desired. from the call indicator, she inserts plug 1 in the jack J of the desired line. Upon the insertion of plug P into jack J, a circuit is closed from ground through re ay 221, sleeve of the jack and plug, conductor to battery through relay 209. Relay 200 operated, closes the talking conductors 1410 and 150 to conductor 1 1 1 and thence through the subscribei"s station E. Relay 20.) operated. also operates relay 207 over a circuit from ground on its inner right front contact, conductor 224, left back contact of relay 208, right back contact of relay 206, through the winding of relay 207, conductor outer right front contact of relay 128, conductor 1 13 to battery thereby operating relay 207. The operation of relay 209 also opens the circuit through relay 203, releasing it. Relay 207 operated opens the talking leads 141-0 and 1 11, and connects ringing lead 227 and ground to conductors 150 and 151 to ring the called subscriber B. Relay 203 released. releases relay 323 in the recorder circuit, thus extinguishing the call indicator lamps. The release of relay 203 also releases relay 103 which in turn releases relay 104. The release of relays 103 and 104C opens all leads between the trunk and associated recorder circuit. At this time the register and recorder circuits are released as described in the patent to A. C. Powell by the operation of relay 346 which operates upon the release of relay 301. The winding of relay 207 being connected in parallel with lamp 210 prevents the lamp from lighting but allows the relays to operate. \Vhen the called subscriber answers by removing the receiver from the switchhook, relay 208 op crates in series with the subscribers set. Relay S operated, removes the shunt from around relay 206 allowing it to operate in series with relay 207. Relay 206 operated, locks under control of relay 200 over a circuit from ground on the right front contact of relay 209, conductor 22 1, winding and front contact of relay 206, conductor 225, outer right front contact of relay 12S, conductor 1 1-3 to battery and short circuits relay 207 through its front contact, thereby releasing it. The release of relay 207 disconnects ring ing current from conductors 150 and 151 and connects these conductors to conductors 140 and 1 11 and thence to the repeating coil. Lamp 210 is now shunted by relay 206, preventing it from ligl'iting until the calling subscriber replaces the receiver on the switchhook.

Relay 136 operates at this time over a cir cuit from battery, winding 142 of the repeating coil through the winding of relay 136, conductor 1 11 left back contact of relay 207., conductor 151 through plug P, jack J and the subscribers set, conductor 1%, outer left front contact of relay 209, conductor 150, right back contact of relay 207, conductor 1 10, winding 1.415 of the repeating coil to ground. The operation of relay 136 closes a circuit for operating relay 107 from baltery through its winding, front contact of relay 136, conductor 213 inner left front contact of relay 128, to ground on the left front contact of relay 102. The operation of relay 107 reverses battery over leads 108 and 117 through its contact for the purpose of registering the call at the distant end of the trunk.

hen the receiver at calling station A is replaced on the switchhook, the relay 101 releases in turn releasing relay 102 which opens the holding circuit for relays 12S and 122. The release of relay 128 opens the holding circuit hereinbefore traced for relay 206, and removes the shunt which was traced through its right outer front contact from around disconnect lamp 210, allowing it to light over an obvious circuit from battery through lamp 210 to the right front confor won: at a tor-"s positions. nelay: junction with register Ll'CS 0, 210, 420, 430, hi2, 4:12, 4:21? and also used for indi- "Lg at the right and left adjacent posi- The operation of these relays and reg); '.sters lure been tally deccrihed in. the patent to A. C. Powell and as these pieces o apparatus are not essential to an understandiiu of the present invention a description there-- of Will not be given herein.

lVhat is claimed is:

1. In a telephone system, an originating); oiiice, a calling line terminating therein, a :alling device associated therewith, a terminating oilice, called lines terminating; therein, means for establishing a connection between said offices, an operatofis position in said latter otiice, a call indicating; device at said operatofis position, said int icating device having a plurality of registers for registering; digits of called line numbers trans mitted thereto by said calling device, and means ii said indicating device for ahsorlr ing Without registering the impulses correspondingly LO one of the first digits transmitted by said calling device.

2. In a telephone system, an originating otlice, calling line terminating therein, a calling device associated therewith, a terminat-ing office, called lines terminating therein, means for establishing a connection between said otlices, an operators position in said latter office, a call indicating device said operators position, said indicating device having a plurality of registers "for registering digits of called line numbers transmitted thereto by said calling, device, and a relay in said indicating device for absorbing the impulses corresponding); to one of the first digits ti'flDSHlllllGtl by said calling device.

3. In a telephone system, an originating o'tiice, a calling line terminating therein, a calling device associated therewith, -a terminating otlice, called lines tern'iinating therein, means for establishing a connection he tween said otfices, an operators position in said la 'ter oiiice, a call indicating; device at said (meratofis position, said indicating device having a plurality of registers for reglSlQi'll'lg digits oil? called line numbers transmitted thereto by said calling device, and 132121113 in said indicating device for absorbl are used with key 202 ljacent righ ind lett operaand 345 in con t it ing Without registering the impulses corresponding; to the first digit transmittedto said indicatii'ig device by said calling device. L in a telephone system, an originating otl' a terminating otlice, called lines termina .5; in said latter oilice, means for establishing a connection etween said oiiices, an operators position in said latter 0 a call indie-a device at said operator's J sition, indicating device having a plurality of digits of called line ii. said originating oitice tor series ot ii'npulscs corre d line numbers J 11d means in said indinboingi \vi out registeri such series of impulses. system, an originating 1 called lines termice, means in said :nsmitt series of spending to the oflice cone and nations of called lines, automechanism responsive to certain of said series of on ice code impulses establishing a connection between said an operatofs position on said termiotlice, a call indicating device at said -1 having a plurality of registers tor V the numerical designations of d l nes in accordance vith series 0 ms emitted thceto from said 0 a mace, and means, in said indicating "cc for absorbing: the la t of said series of code impnlsis Without registration thereof.

6. ln a telephone system, an originating otlice, a terininatin' tlice, means for estal lishing a connection between said ollices means in said first otice for transmitting series of impulses to said second oiiice, means in said second office for registering impulses transmitted to said second oiiice, and means at said second oiiice for absorbing one of the first. (it said series oi impulses.

ln a telephone system, an originating: otiice, a terminating otiice, means for establishing a connection between sa d oliices. means in said first o'llicc for transmitting se ries of impulses to said second o'liice, means in said second oilice for r u erine; impulses transmitted to said second otl'ice, and means said second OliiCG for absorbing the first one of the series of impulses received at said second ofiice.

In testimony whereof, I have signed my name to this specification this 16th (lav (it June 1925. I

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